A class of agents known as .beta.-adrenergic blocking agents are available which effect cardiac, vascular and pulmonary functions and can be mild antihypertensives. Specifically, these agents have the capability of reducing heart rate, counteracting vasodepression and suppressing bronchodilation. .beta.-adrenergic blocking agents, their chemical structure and activity, are disclosed in "Clinical Pharmacology and Therapeutics" 10, 292-306 (1969) and in M. S. Large, et al., J. Med. Chem., 25, 1417-1422 (1982). One .beta.-blocker known as timolol is structurally related to the compounds of this invention and is disclosed in U.S. Pat. No. 3,655,663.